Process of making neo-arsphenamines



a e as RAUL GEORGE DOHR, 03F YONLERS,

T0 PHILIP A. HUBER, 61E HASTINGS-C;ll-H'UDSON, YORK.

PROCESS GE IWIAIIING NEO-ARSPHENAWLINES.

N0 Drawing.

chloride) by means of formaldehyd-sulphoxylate (lIO -CH -OS -O-Na).

Errsphenainine, owing to its hydrochloric acid content requires neutra ization before administration and the neo derivatives were prepared in order to eliminate this. But in practise the neo derivatives were found to arsphencontain less of the active principle, amine base, than the theory called for. a matter of fact neoarsphenamines have only an arsenic content as the S. Public Health Service found, of to 20%, whereas they should be if pure and anhydrous. In the literature a number of methods of preparation ar mentioned, but they all lead to a more or less impure prodt as not. liorndorfer and lleuter (U. S. P. l 053 300. lteissue l3 ,WLVQ in detail a number of methods of preparation and mention one or two other methods, but fail to specify details or other disclosures sufficient to make a pure product. I

Thus in Example 1. (Kornderfer and Router) a solution of neoarsphenamine is made which must contain as impurities, sodium chloride, excess formaldehyde sulphoxylates and sodium sulphite, all resulting from the reaction of the constituents added. in examples 2 and 3 the precipitation of the complex with 100 cc. hydrochloric acid gives a purer substance, but the filtration of this complex free from mother liquor is practically impossible, owing to its gelatinous nature, and more or less remains impure.

In examples l and 5 the product is also highly contaminated and no details were suggested for eliminating these impurities.

In the manufacture of pure neoarsphenamines quick filtration and washing is essential as the reaction goes on as long as the Application filed December 31, 1921.

Serial No. 526,295.

reagents are in contact with the moist arsphenamine. The mother liquor always iontains formaldehyde sulphoxylate if previous disclosures are followed and if mad with the ell-hydrochloride of arsphenamine base, must contain decomposition and reaction products of this reagent, sodium chloride, sodiumsulphite, and if precipitated finally as disclosed, from alcohol, must contain alcohol of crystallization and also alcohol of combination, or in combination.

New I have discovered that an excess of the reagent is not necessary and if properly used, the sulphinic acid complex will pre cipitate or crystallize out of aqueous solutions slowly, so that large particles or crystals are obtained, with the result that t iis complex can be filtered quickly, easily and on a large scale, and washed easily with hydrochloric acid and water, so that the sulphinic acid complex can be obtained chemically pure and therefore convertible into its sodium salt, the neo-arsphenamine, with high purity. By evaporating the neutralized complex in a high vacuum and avoiding the alcohol precipitation, the neo salt will contain 29.88% arsenic indicating two molecules of water of crystallization and after further drying may contain 30.99% indicating one molecule of water of crystallization, or even close to 82.19% the amount for the chemically pure and anhydrous. It may also be precipitated by acetone or another solvent that is inert under the conditions of the experiment and in the presence of this complex.

The principal parts of my discovery are that, by using a monoor di-hydrochloride of the arsphenamine base and adding enough formaldehyde sulphoxylate to make a monosulphinic acid (1 mole) the neo base will slowly but steadily precipitate or crystallize as it is formed, easily iilterable and washable. It must be understood that enough hydrochloric acid must be present at all times to keep the sodium salt of the complex from forming, otherwise it will not, of course, allow the complex to precipitate. Another important matter is the washing of the complex, after filtering, with dilute hydrochloric acid. This decomposes sulphites that may have been occluded in the precipitate and removes the products. In other words removes from the complex the unstable and catalytic substances.

I prefer to go about the preparation of a pure neo-arsphenamine as follows:

EwampZc J.28.74: grams (mole/20} of arsphenamine (the dihydrochloride of the base allowing for two molecules of water of crystallization) are dissolved in 250 cc. of water and reduced to a temperature of 20 G. Then while stirring are added one mole of formaldehyde sulfoxylate (5.9 gr: ms if pure dissolved in ten parts of wat r). Both the arsphenamine and the sulfoxylate solutions should be perfectly clear; if net they must be filtered until clear. ii ithin five to ten minutes a precipitate begins to form occasionally a gel is formed first, and within an hour the precipitation is complete. The liquor is then filtered off and the precipitate washed preferably with QN/l hydrochloride acid and finally with distilled water but it is to be iiindersteod that a weaker hydrochloric acid may be used, as l have found by experiment that the use of a weaker acid is entirely satisfactory. In these last operations, washing with water and in the following operations, air is to be excluded as much as possible, by operating in inclosed vessels or by the use of an inert The moist complex base is then dissolved in sodium carbcnate or sodium hydroxide solution, filtered and evaporated in a high vacuum with the aid of heat, or the clear solution of the neutralized complex is precipitated with ten volumes of acetone.

The nee-arsphenamine is left as a dark orange or brown amorphous substance when evaporated, as a yellow powder when precipitated with acetone. This powder dissolves slower in water than ordinary impure nee-arsphenainines as it has in commo with pure arsphenamine a tendency to gelatinize. The arsenic content will vary depending' on the ei'i'iciency of the washing, purity of reagents and the extent of drying, from 29.5% to 32.0%.

Example F3.5el:.9 grains of arsphenamine base (3 mole/20) which previously has been washed with water at 50 to free it from impurities resulting from adherence of the mother liquor, are emulsified with small quantity of water in order to obtai uniform emulsion of the base, free from lumps. In other words like a thick cream. Then Qll/l hydrochloric acid added little by little until the base is dissolved. This amount of hydrochloric acid should be not more than one gram mole equivalent, so that in solution a mon-hydrochloride of the base results. In this example it would be 150 cc.

QN/l hydrochloric This solution in of normal or cc. of acid would be sullicient.

turn is fi ered clear to tree it from insolu- (i5 lle matter. precautions have to be t exclune air from these acid solu- Zj been found that contrary to mixtures of Ehrlichs and em methods, the acid mix- 21 oxidize very slowly. To

- "hen adcel with -a one mole (17.? pure) of formaldehyde sulf 3 solved in ten parts of water, when lig i 1ft which i ""alinalion 2) t0 I nee-comp an hour.

This complex base then washed llI-fill'OClll'iiC acid, water, and fill'i'llcz treaed as in Example 1.

claim l. The process of inali'ing 1ieo-arspl1e11- amine which consists in having the torn "ldehyde 'oxylate to act on arspheuamine ltlOH suiiieieutly ec-coniplex as a: 1a,. into a as descii ed.

The process of making non-aria amine which consists in havin hyde sullo to act en a base in an solution su fcie y to precip ta'te the nee-complex as is foru'ied, removing the lili'ftlli'l liquor and impurities and converting it into a Ffitildli'l salt.

3. The process of making i'ieo-arsplienamine which consists in having formaldeon ars jr-heuruiine hyde sulfoxyiate to act base in an ac solution iently strong to precipitate the o-c I it is o med, removing purities by washi I with aqiicous hydrochloric acid and and convening it auto a sodium Sti t el. The process of making neo-arsphenamine which consists in having formaldehyde sul late to act on ai'sphcnauiine in an acid don suliicicntly strong to precipitate the nee-complex as it is formed, removing impurities, and dissolving in alkali obtaining the dry sodiuizi salt bv poration. I

i m A PAUL GEORGE lJUl'l l. 

